32 
for the preservation of ties were abandoned. But at present the ease is 
different. In rnauy localities timber is two or three times as expensive 
as it formerly was. Chemicals are much cheaper aud money bears a 
lower rate of interest, so that, upon the score of economy alone, it will 
now be expedient to do what was unwarranted a few years ago. Little 
inquiry was made as to why so inany of the preserving processes failed. 
THE DECAY OF TIMBER AND TIES DUE TO THE GROWTH OF VARIOUS 
KINDS OF FUNGI. 
In dry situations, as in roofs of buildings, or when submerged in 
mud and water, seasoned wood will last for centuries ; but it decays in 
places where it is warm and moist (from 40° to 120° Fahr.). Formerly 
the decay of timber was generally ascribed to slow combustion (Liebig's 
Eremacausis), but it is now known to be due to various kinds of fungi, 
the presence of many of which microscopical investigations have dem- 
onstrated. 
As regards the relative position of the fungi in the scale of plant-life, 
it is perhaps only necessary to say they are a great group of plants of 
low organization, destitute of chlorophyll, and bearing neither leaves nor 
flowers. Instead of seeds they produce microscopic spores, which are 
freely disseminated by wind and water. They are dependent chiefly 
upon higher plants for their nutriment, appropriating the already elab- 
orated material found in the tissues of these hosts. Nearly 50,000 
species of fungi have been described, many of which grow on or in the 
wood of trees. 
A large number of the measures formerly adopted to prevent and check 
decay, especially that of unseasoned wood, by confining the moisture, 
were the most effective in causing the fungi to grow, inducing, it is be- 
lieved, the decay of the wood. Thus it is a well-known fact that paint 
ing green timber will hasten rather than retard its decay ; the paint, 
by retaining the moisture, furnishes a necessary condition for the ger- 
mination of the inclosed spores. This also is probably the explanation 
of the failure of so many of the other preserving processes. The chem- 
icals, or other substances used, formed an exterior coating* like paint, 
thus retaining the moisture and allowing the fungi to grow on the in- 
side, causing the so-called u dry-rot." If the timber be thoroughly sea- 
soned, an exterior protection from moisture is sufficient to prevent de- 
cay. The rotting in four or five years of many of the earlier wooden 
bridges, which were painted before they were seasoned, is familiar to 
all railroad men, while those unpainted lasted much longer. So, too, 
unpainted covered wooden bridges were found to be the most durable, 
from the fact that the timber was kept so dry as to preclude the attacks 
of fungi. The timber, if not too large, became thoroughly seasoned , and 
in that condition was practically indestructible. 
*See Carbolineuni as a Protection against the Decay of Wood, p. 104, 
